Spark plug



Nov. 2, A1937. w. P. lNNEs, JR 2,097,460

SPARK PLUG l Filed Dec. l2, 1934 I I7%/ 2% 21M Patented Nov. 2, 1937 UNITED STATES PATENT OFFICE SPARK PLUG Applientien December 12, 1934, serial No. 757,206

6 Claims.

of the engine in which the main charge is fired,

whereby the main charge is red by the jet of l5 flame issuing from the chamber in the plug.

One of my objects is to provide a construction of spark plug wherein accurate adjustment of the electrodes of the plug relative to each other to produce the proper spacing thereof, one from the 0 other, may be effected with ease and great facility.

In connection with another object of my invention and relating to the chambered type of spark plug, it may be stated that as these plugs :5 have hitherto been provided, both of the electrodes are located wholly within the chamber iny the plug, resulting under certain conditions of use, in the befouling of certain of the electrodes by the accumulation thereon of carbon and/or :o oxide with consequent impairment of the plug for functioning due to the fact that the temperature within the chamber in the plug, and which is lower than that in the main` combustion chamber of the engine, is not suflicient to maintain the `5 electrodes hot enough to clear them of such befouling accumulations. y

It is my object in this connection to provide a spark plug of the chambered type in which the heat generated by the burning fuel in the engine shall be utilized to an extent sufficient to maintain the electrodes free off carbon and oxide deposits, thereby to insure theproper functioning of the plug, especially under the varied conditions presented by different engines. y

Another object is to provide'improvements in spark plugs of the chamberedtype to the end that the plug, as to its construction, will follow the lines in general ofthe standardv designs of spark D plugs; and other objects as'will be manifest from the following description.

Referringto the accompanying drawing in which I have illustrated my invention as embodied in. s'e veral different forms of structure: Figure .-1 is a view in longitudinal sectional ele- (Cl. 12S-169) DEC. 12 1939 vation of a spark plug of the chambered type and embodying my invention.

Figure 2 is a bottom plan view of theplug of Fig. 1. v

Figure 3 is aview likeFig. 1 of the lower end 5 of a spark plug constituting another embodiment of my invention in aplug -of the chambered type; and

Figure 4', a view in side elevation of a standard form of spark plug of the unchambered type modified to embody one of the kfeatures of my invention.

In accordance with the particular. embodiment of my invention illustrated in Figs. 1 and 2, the plug comprises a metal shell 5 open at its oppo 15 site ends at which it is internally and externally threaded, respectively, as represented at 6 and 1, the internal thread 6 being provided to receivev a threaded gland represented at 8 for a purpose hereinafter explained and the thread 'I being pro- '20 vided for the screwing of the plug into the usual threaded hole provided in the cylinder of an internal combustion engine for receiving a spark plug.

The plug also comprises a, center, or core, member 9 of kcurrent-insulating material, as for example porcelain, which seats at its enlarged annular portion I0 upon an annularr seat I I in the interior of the shell 5, the core 9 being held in place by the gland 8. 30

The lower end I2 of the core 9 is of less diameter than the space within the shell 5 into which this part of the core extends, the core-end I2 reaching short of the bottom of this space, thus forming, with the shell 5, a chamber I3 into 35 which, it is designed, aportion of the charge of combustion mixture enters from the combustion chamber of the engine to which the plug is' applied, to be fired therein for producingl the projection of a jet of name through the lower open 40 end of the chamber I3 and into the main'charge in the combustion chamber of the cylinder to re the latter, the opening at the lower end of the chamber I3 and which is restricted as compared with the diameter of this chamber, being indicated at Il. The size and shape of the chamber vI3 and the dimensions of the opening I4 are such, as shown, as to cause the spark plug to loperate with the maximum efficiency and dependy ability'in the ring of the main charge in the 50 combustion chamber by means of the jet of ame produced in the chamber of the plug.

'I'he electrodes of this construction are shown at I5 and I6, the electrode I5 being shown as of common form and provided .centrally in the core 9 with its lower end portion I'I projecting part 'way into the chamber I3.

The electrode in preferably, but not necessarily of general U-shape, is carried by the` metal shell'5, extends across the lower end of this shell and has a portion I8 which projects upwardly through the opening I4 and into the chamber I3 to a. position for proper cooperation with the electrode portion I'I to form a suitable spark gap within the chamber I3.

Preferably the electrodes are so proportioned and arranged as shown in Fig. 1 that the electrode portion I8 extends to a position above the lower extremity of the electrode portion II as shown by dotted lines in Fig. 1,-the electrode portion I8 extending alongside and lengthwise of the electrode portion I1 thereby forming a spark gap extending crosswise of the plug. The electrode I6 has a portion represented at I9 which extends crosswise of the lower end of the shell exteriorly of the chamber I3 and preferably in suitably spaced relation to the underside of the shell 5 as shown, the portion I6 of this electrodewhich directly cooperates with the electrode portion I1 to form the spark gap extending upwardly from the portion I9 and through the opening I4 into the chamber I3.

To provide an electrode I6 having the characteristics above noted, it is preferred that the electrode be provided of general U-shape as shown and above referred to, the electrode being supported in position on the shell 5 by the attachment thereof to the shell 5 at the leg portion 20 of the electrode, the portion 20 which opposes the leg comprising the electrode portion I8, being shown as fitted into a downwardly opening socket 2l in the shell 5.

The provision of the electrode I6 with a portion which extends exteriorly of the chamber I3 and in a position in which it is subjected to the heat generated by the burning gases in the combustion chamber of the engine cylinder, as shown and described, is of great advantage in a construction of this kind due to the fact that the electrode I6 becomes the heating element of the device and objectionable deposits of carbon and scale on the electrodes is avoided, it being understood that each time a fresh charge of combustible mixture is introduced into the engine cylinder, (a part of which enters the chamber I3), the electrode I6 becomes covered with the combustible'mixture and this electrode being very hot, complete combustion of the mixture on the electrode is effected, upon the firing of the charge, the adaptability of the electrode I6 for performing as the heating element of the device being augmented by reason of its relatively great length as compared with an electrode located wholly within the chamber of the plug. By the construcp tion shown I am thus enabled to utilize the high heat in the combustion chamber of the engine,

and which is considerably higher than that which exists in the chamber I3 of the plug, for the maintaining of the electrodes clear of carbon and oxide deposits.

Furthermore, as will be understood, the electrode I6 is not only subjected to the action of the heat generated by the burning charge, causing it to become heated as stated and minimizing carbonization; but is also subjected to the mechanical force exerted against it by the surging of the vapor into the plug-chamber and the blasting force of the gases ignited in the plug-chamber and discharged through the opening in the plugI into the combustion chamber, this force serving to blow oil accumulations on the electrode I6 which is directly in the path of the blast.

The spacing of the electrode portion I9 from the underside of the shell 5 is of advantage as should there happen to be a tendency to accumulation of carbon on the electrode I6, the danger of such accumulation building up to an amount sufficient to span the space between the underside of the shell 5 and the electrode I6, thus impairing the operation of the plug, is avoided.

In accordance with one phase of my invention provision is made for adjusting the electrode I 6 relative to the electrode I5 for the production of the desired length of spark gap.

In accordance with the disclosure in Figs. 1 and 2, the adjustability referred to is provided for by providing such looseness of t of the electrode portion 20 in the socket 2| as to permit the electrode I6 to be rotated about the portion 20 as an axis, but suiciently tight to maintain the electrode against accidental displacement from adjusted position, the wall of the opening I4 being recessed as represented at 22 to provide the desirable clearance between the electrode portion I8 and the wall of this opening to insure against objectionable bridging by carbon deposits.

By the arrangement shown it is possible to quickly and accurately adjust the electrodes for the desired length of spark gap, such adjustment, when the electrodes sidewise lap each other as shown in Figs. 1 and 2, being readily and easily A effected by sliding a suitable gage stick lengthwise `through'the opening I4 into the space between the electrodes I5 and I6.

It will be noted that in the particular construction now being described the distance between the electrode portions I8 and 20 is substantially the same as that between the electrode portion 20 and the electrode portion I1, whereby the swinging adjustment of the electrode I6 is particularly useful in providing for the desired length of spark gap.

Certain features of the invention may be utilized in a construction in which the cooperating portions of the electrodes instead of lapping sidewise as in Figs. 1 and 2, extend in endwise spaced relation whereby the spark gap extends` lengthwise of the plug instead of crosswise thereof.

Fig. 3 shows the plug of Figs. 1 and 2 modified 1n the, particular just referred to.and wherein the same numerals are used as in Figs. 1 and 2, the only substantial change being in the provision of the electrode portion I8 as suiilciently short to extend in the desired spaced relation to the electrode portion I1 in the direction of the length of the plug when the electrode is swung to a position in which these electrode portions longitudinally aline.

The electrode adjustment feature as described above in connection with Figs. 1 and 2 may also be utilized in a spark plug of the standard or conventional unchambered type, Fig. 4 showing such a spark plug modied to embody this fea- 23, the porcelain core at 24, the gland holding the core to the shell, at 25, and thel central electrode provided within the core 24, at 26.

The other electrode of this plug, in accordance with ,then present invention is represented at 21 and is preferably of general U-shape shown. its

aoomco legl portion 2l extending along the side of the electrode 28 as described of the electrode portion While I, have illustrated and described my invention as embodied in several particular forms of construction, I do not wish to be understood as intending to limit it thereto as the same may b e variously modified and altered and the invention embodied in other forms o! structure without departing from the spirit of my invention.

What I- claim as new, and desire to secure by Letters Patent, is:

l. A spark plug comprising a shell having a chamber formed therein, a wall portion adjacent for said chamber adjacent the end of said plug,`

said wall having an opening formed therein adjacent the longitudinal center line of the plug and o! substantially less diameter than the diameter of said chamber, a central electrode e'xtending into said chamber, and a substantially U-shaped; ground electrode extending across a substantial portion of the outer side of said end wall to adjacent the central portion of the plug and thence into said chamber tofadjacent said central electrode.

3. A spark plug comprising a shell having a chamber formed therein, said shell having a transversely extending wall portion adjacent one of its ends providing an end wall for said chamber closely adjacent the end of said plug'sald end wall having an opening formed therein adjacent the longitudinal center line of the plug, a central electrode extending into said chamber, and a substantially U-shaped ground electrode extending a substantial distance across `the outer side` of said end wallto adjacent the central portion of the plug and thence into said chamber through said opening and into overlapping rela-f chamber formed therein and providing side walls for saidchamber. a transversely extending wail atone end of said shell providing an end wall for said chamber of substantially lesser thickness than the thickness of said side walls, said end wall having an opening formed therein adjacent Vthe central longitudinal line of the plug and of v substantially lesser diameter than the diameter of said chamber, a central-electrode extending into said chamber, and a substantially U-shaped ground electrode extending -across a substantial portion of the outer sideot said endwall to ad1- jacent the central portion of the plug and thence into said chamber adjacent the central portion thereof to adjacent said central electrode.

5. A spark plug comprising a shell having a chamber formed therein and providing side walls for said chamber, the inner surface of said side walls being inclined toward each other and t'erminating at their lower ends in a transversely extending wall at one end of said shell providing an end wall for said chamber of substantiallyy lesser thickness than the thickness of said side Y walls, said end wall having an opening formed therein adjacent the longitudinal center lineA of the plug and 'of substantially lesser diameter than the diameter of said chamber, a central electrode extending into said chamber, and a ground electrode extending across a substantial portion of the outer side of said end wall to adjacent the central portion of the plug and thence into said chamber adjacent the central portion thereof and into overlapping relationship with respect to said central electrode.

6. A spark' plugcomprising a shell having a. chamber formed therein and providing side walls for said chamber, the inner surface of saidside Walls being'inclined toward each other and terminating at their lower ends in a transversely extending wall at one end of said shell providing an end wall for said chamber and of substantiallyA lesser thickness than the thickness of said side walls, said end wall having an opening formed therein substantially concentric with the longitudinal center line of the plug and of substantially lesser diameter than the diameter of said chamber, a central electrode extending into said chamber, and a ground electrode extending across a substantial portion of the outer side of said end wall to adjacent the central portion of the plug and thence inwardly through said opening into said chamber adjacent the central portion thereof and intooverlapping substantially parallel relationship with respect to' said central electrode. Y

WALTER P. INNES, Jn. 

